Wave-responsive device.



C. D. BABGOGK- WAVE RESPONSIVE DEVIGE.

APPLIOATION FILED AUG.27,190'8.

v1Pate11ma Oct. 27, 1908.

\\\\\\\\\\\\\\\ III inventor: I

m Atty uN-iTED STATES PATENT OFFICE.

oLiFFbRD D. BABOOK,OF NEW YORK, N. Y., ASSIGNOR T0 UNITED WIRELESSTELEGRAPH COMPANY, on NEW YORK, N. Y., A CORPORATION OF MAINE.

wsvn-nnsronsrvn DEVICE.

Specification of Letters Patent.

A pp1ication filed August 27, 1908. Serial No. 882,196.

'- To all whom 'it may concern:

Be it known that I, CLIFFORD DIi-BAB- coon, a citizen of the UnitedStates, residing at New York, in the county of New York and State of NewYork, have invented a new and useful Wave-Responsive Device, of whichthe following is a specification;

This invention relates to improvements in mechanism for wave responsiveor detecting devices to be used in the receiving apparatus of a Wirelesstelegraph s stem,

. and theobject is to obtain a sim Is an cheap device in whichto employwe known materials as the sensitive substances.

The invention will be best understood from a description of oneparticular embodiment thereof which is illustrated in. the accompanyingdrawing in which Figure 1 is a view in side elevation of my improvedreceiving device, and Fig. 2 is a vertical sectional view of the artsdisassembled to show clearly the relative arrangement thereof.

' obtain a valve or trigger eflect to releaseithe energ of an auxiliarysource of ele ctromotive orce to operate a telephone receiver.

, This is a well-known electrical property of this substance,: which hasbeen used as a.

motor starter. I therefore utilize "this characterittic by inserting amass or single crystal of such substance in the local or in-- apparatusvdicating circuit of the receiving contalnlng also the requislteauxiliary source a of electromotive force and potentiometer forregulatin the same, ceipt of the fiertz waves and passage of theoscillations caused thereby through the crystalline material, a flow ofcurrent from the auxiliary source takes place in said local circuitwhich may be detected by any suitable form of indicating instrument,such as a telephone receiver. The detector should be connected in theusual way across the terr minals of the indicating device.

whereby. upon re-.

In the embodiment of my invention shown in the drawing, the devicecomprises a metallic base plate'G upon which is mounted an insulatingstandard I secured thereto by a screw V. Mounted upon said standard lgmeans of a screw T is a spring contact arm between which and anadjustable contact 6 Patented Oct. 27, 1908.

also mounted upon the base plate G, the carborundum X or other sensitivematerial is held, said contact b being provided with .a

knurled adjusting head B. e

In order to adjust the ressure of the spring contact arm S upon t esensitive element 1% I provide an adjusting screw P mounte inan arm Awhich is secured upon the standard I and above the arm S, also by. thescrew T, a set nut N being provided to hold the parts firmly inposition.

In inserting the crystalline mass between the s ring arms and thecontact I), the latter is a justed until said mass will just slip easilyin between the two when the spring is in normal the screw Said screw isthen adjusted to position or not under pressure from bring the s rin Sdown upon the crystal and a hold it at t 1e esired; ressure betweenitself and the contact I). y means of this construction alight but firmand adjustable contact may be maintained upon the sensitive element Xwithoutdanger of crushing the crystalline structure thereof and byreason of the adjustabilit ofcontact b the spring arm Sneed be de ectedbut to a' slight de' J gree in makin contact with the sensitive elementwhere y the spring is always maintained at its condition of, greatresiliency,

thus permitting any degree of lightpressurg;

on said. member. This feature is very'deg sirable as for greatestefliciency of the dv vice it'is necessary that the area of contact withthe sensitive member be as small as possible consistent with the firmvholding thereof between the parts S and b.

For connection of the device in circuit, a binding nut B is provided onthe screw T, the other connection being effected by the screw whichsecures the device to itsv sup-- port, for the reception of which screwa recess L is provided in the rear end of the base plate,

The crystalline substances used with this device should in use becarefully shielded or protected from the effects of atmospheric changesof temperature andlhumidity, as by inclosure in a moisture-proof orheat-insulating receptacle, and by the inclusion in the receptacle of amoisture-absorbing material.

are inoperative, owing probably to a crystalline formation not ar aptedto utilize the resistance-varying properties of a crystal. A singledetached crystal usually gives better results than a mass or body ofcrystals. The best operation is obtained by placing the edges, and notthe surfaces, which are insulating in character, oila single crystal incontact with the spring S and contact I) in order to obtain a smallarcaof contact with a single crystal so as to obtain a maximum effect ofthe heating by the oscillations and a resulting greater abrupt change inthe variation of the internal resistance of the crystalline substance.The surfaces of the crystals are apparently chemically and physicallydifferent from the edges, and so are non-conducting. A loose contact inthe circuit of any part of the crystal does not give good results, andfor this reason the spring S is an important feature as it insuresasuflicient action of the oscillatory current to oeratively vary theresistance of the crysta This 'detector owes its efiiciency to the hightemperature coefiicient of the substance used and the small size of theeil'ective contact which limits the active portion of the substance to avery small volume. In a commercially sensitive detector the operativeportion of the carborundum is a minute pyramidal mass, about athousandth of an inch on an edge, and containing about a billionth of acubic inch of the substance. The ciiective area of contact with thecircuit is also very small, being of the order of a few millionths of asquare inch.

The importance of using a potentiometer to quite accurately regulate theelectrometive force of the auxiliary source is shown by the fact thatthe curve of conductivity of the device is flat at zero upto adifference of potential of about one-half a volt across its terminals,when the curve rises rapidly, its steepest rise-being between one voltand one and one-tenth volts, where for an increase of potential of tenper cent., the conductivity increases more than one hundred per cent. Ata potential difference greater than one and one-tenth volts, the rise inconductivity is decreased rapidly. It has been demonstrated in practicethat with carborundum,

the maximum response in the telephone from a distant'station 1s betweenone and one and two-tenths volts. From these 'facts it is obvious and ishereby recommended that to obtain practical results, a battery should beused in order to obtain an operative condition of conductivity of' thesubstance which cannot be had witheut'a potential difference of at leastmore than half a volt; and that a potentiometer should be used in orderto constantly maintain under varying conditions, a potential differenceacross the terminals of the device of between one and one and two tenthsvolts.

When during use, a given mass becomes inoperative, this device offers aready means of replacement by a new operative mass or crystal.

It is always necessary in practice to connect this device in series withan auxiliary source of clectro-motive force such as a primary battery,because none of the energy of the received oscillations is translatedinto a current suitable for operating the indicating dcvice,'and so abattery is necessary to operate said device by the abrupt change in theelectromotive force of the battery circuit caused by the variation ofthe internal resist ance of the mass of material due to the action ofthe received oscillations.

it has proved to be impossible in practice to use'the device without abattery or other suitable source of electromotive force. A potentiometershould also be used to regulate the battery action. In other respectsthe device may be used in the circuits of wireless telegraphy apparatusas well known to those skilled in the art.

I claim:

1 A wave responsive device, which comprises a metal base, means forconnecting the base to one side of the electric circuit, an adjustablecontact mounted on the base as a support for a sensitive substance, aspring contact arm having a free end operatively positioned oppositesaid contact support'to bear lightly on such substance, an insulatingstandard mounted on said metalv base as a support for the other end ofthe spring conend operatively positioned opposite said con-- tact tobear'lightly on such substance, a support for the other end of thespring contact, adjustable means intermediate the free and supportedends of the spring contact arm to press the free end firmly against thesensitive substance, and a support for said adjustable means.

3. A wave responsive device which comprises an adjustable contact, aspring contact arm having a free end operatively positioned oppositesaid adjustable contact, a support for the other end of the springcontact, means intermediate the free and supported ends of )ortin armmeans-for connectin t e {TI J of which is operatively positioned withrespring on the insulating standard, means for with respectto saidcontact, an adjusting the spring contact-arl'n to adjust it with respectto the adjustable contact, and. a support for said ad usting means;

4. A wave responsive device which comprises a metal 'base, an adjustablecontact mounted thereon, an insulating standard also mounted thereon, asprirw contact supl ported on the insulating standhrd and opercontact,an adjusting screw bearing on said spring contact intermediate the pointof support and the operatively positioned part of the spring contact, asupporting arm for the adjusting screw mounted above the contact .hol'dig together in position the-insulating stan ard, the contact spring, andthe su spring-supporting arm to one terminal of the circuit, and means[or connecting the metal base to the other terminal of the circuit.

5. A wave responsive device, which colnprises a base, a contact mountedtherein, a standard mounted on the base, a spring contact arm mounted onsaid standard so that one end of the am: is operatively positioned screw'bearing'on' the spring contact arm between its point of support and itsoperative end, and a support for the adjusting screw also carried bysaid standard. v 6.-A wave responsive device, which comprises a contact,a spring contact arm one end s pect to said contact, a support for thespring contact, adjusting means acting on the spring contact between itspoint of support and its operative end, and a support for the adjustingmeans; 1

.1 7. 'A wave responsive device which comprises a conducting base, anadjustable contact mounted thereon, an insulating standard mounted onthe base, a spring contact mounted on said insulating standard andcoarse to one side of the electric circuit, an ad-' justable contactmountedon'the base as a support for a sensitive substance, a springcont-act arm. having a freeend operatively positioned opposite saidadjustable contact to bear lightly on such substance, an insulatingstandard mounted on said metal base as a support for the other end ofthe spring contact arm, said standard having opposing threaded o )eningsseparated by an integral insulating arrier, a screw entering one of saidopenings to secure the standard to the metal base, an adjusting screwbearing on the spring contact arm intermediate its ends to press itfirmly as well as lightly against the sensitive substance, a supportirwarm for the adjusting screw and mounted above the end of the springcontact arm which is seen red to the standard, a-screw entering thesecond opening in the insulating standard to hold the shring contact armand its supporting arm to the insulating standard, a set nut on saidscrew for securing together the standard,

spring contact arm and its supporting arm, and a binding nut on the samescrew as the set nut and above the set nut to securethe circuit lead ofthe other side oi" the circuit.

In testimony whereof I allix my signature in the presence of twowitnesses.

QLII I ORJ) l). BABCOCK.

Witnesses i Jomv 1 I-heonvs,

RALPH (J. .PowmLL.

